I want to use the light probe as a fisheye or spherical camera in Eevee. How can I directly access image data produced by the lightprobe?
The light probe/reflection cubemap is created with 6 image planes in a specialised image format like DDS. It's not spherical.

It is however possible to convert a cross image (composed of 6 renders from each axis into a cross) to a longitude/latitude image using CMFTStudio or Knald Lys.